Dice Roll App

Hi, I'm trying to make a simple dice roller app.
This is what I want to be able to do.

The game allows player throwing an arbitrary number of dice (1-6). Each die can show the number from 1 to 6 if thrown. On each throw you are to calculate the sum of all dice thrown
If your single iteration yielded 7, 11, 21 the player won the game
If your single iteration yielded 13 or 26 the player lost the game
The player can go for maximum of 6 iterations. They can change the number of dice in each iteration.
You must keep the running sum of all iterations. If the sum is exactly 120 the player won the game.

Can anyone tell me how this can be done? I've tried searching for dice roll apps to get some understanding of how it can be done, but didn't find any source code. I'm new to programming, so not exactly sure how this can be done. Any help will be greatly appreciated, thanks. :blackdroid: